Whether　the　global　existence　and　uniqueness　of　strong　solutions　to　n-dimensional　incompressible　magnetohydrodynamic　(MHD　for　short)　equations　with　only　kinematic　viscosity　or　magnetic　diffusion　holds　true　or　not　remains　an　outstanding　open　problem.　In　recent　years,　stared　from　the　pioneer　work　by　Lin　and　Zhang　(Commun　Pure　Appl　Math　67(4):531-580,　2014),　much　more　attention　has　been　paid　to　the　case　when　the　magnetic　field　close　to　an　equilibrium　state　(the　background　magnetic　field　for　short).　Specifically,　when　the　background　magnetic　field　satisfies　the　Diophantine　condition　(see　(1.2)　for　details),　Chen　et　al.　(Sci　China　Math　41:1-10,　2022)　first　studied　the　perturbation　system　and　established　the　decay　estimates　and　asymptotic　stability　of　its　solutions　in　3D　periodic　domain　T-3,　which　was　then　improved　to　H(3+2　beta)r+5+(alpha+2　beta)(T-2)　for　2D　periodic　domain　T-2　and　any　alpha＞0,　beta＞0　by　Zhai　(J　Differ　Equ　374:267-278,　2023).　In　this　paper,　we　seek　to　find　the　optimal　decay　estimates　and　improve　the　space　where　the　global　stability　is　taking　place.　Through　deeply　exploring　and　effectively　utilizing　the　structure　of　perturbation　system,　we　discover　a　new　dissipative　mechanism,　which　enables　us　to　establish　the　decay　estimates　in　the　Sobolev　spaces　with　much　lower　regularity.　Based　on　the　above　discovery,　we　greatly　reduce　the　initial　regularity　requirement　of　aforesaid　two　works　from　H4r+7(T3)　and　H(3+2　beta)r+5+(alpha+2　beta)(T-2)　to　H(3r+3)+(T-n)　for　r＞n-1　when　n=3　and　n=2　respectively.　Additionally,　we　first　present　the　linear　stability　result　via　the　method　of　spectral　analysis　in　this　paper.　From　which,　the　decay　estimates　obtained　for　the　nonlinear　system　can　be　seen　as　sharp　in　the　sense　that　they　are　in　line　with　those　for　the　linearized　system.